Process of hardening metal articles



- G. C. NIXON AND F. C. RAAB. PROCESS OF HARDENING METAL ARTICLES.

APPLICATION FILED OCT-25. I919.

Patented May 9,- 192 2.

INVENTOR. 615026: 6 M fesosezc/z c. 6-

Q MW A TTORNEYJ:

FATE? enonen oonmann Nixon, or nn'rnoir, MICHIGAN,

AND FREDERICK CH.A.RLES

RAAB, 0F SYRACUSE, NEW YORK.

PROCESS OF HAEDENING METAL ARTICLES.

Application filed October 25, 1919.

To all whom it may concern:

States of Michigan and New York, respectively, have invented a certain new and useful Process of Hardening Metal Articles; and we do hereby declare that the following is a full, clear, and exactdescription thereof, reference being had to the accompanying drawings in which like numerals refer to like parts.

Our invention relates to the art of carburizing or case hardening iron or steel. In the usual method of preparing articles of steel for carburization, they are placed in a receptacle or pot for holding the carburizing material, which is sealed to prevent access of the air, and the receptacle or pot and the contents thereof are placed in a furnace and heated to a sufficient degree to incorporate the carbon in the surface of the article and thereby case harden it. The receptacle or pot is filled with the carburizing or case hardening material or compound and the metal articles to be treated are embedded therein. Said material or compound as heretofore used has been in dry powder, granular or pellet form, as desired. a

One difficulty with the foregoing manner of carburizing or case hardening metal articles is the length of time required for treating because the articles are surrounded with a mass of the carburizing material which difficult for the heat to penetrate, and also because of the lack of intimacy of contact thereof with the metal articles. Also, when the charge has been treated, the pot or receptacle is removed from the furnace and the contents thereof discharged or all allowed to cool with the result that there is a Waste of heat.

The nature of our improvement in the present invention will be understood from the accompanying ing description and claims.

In the drawings Fig. l is a plan view of a piece of metal in process of being wrapped and covered by the carburizing material in the manner hereafter explained. Fig. 2 is a plan view of a cam shaft with the cams covered with the carburizing material in a modified way, the right hand half being in Specification of Letters Patent.

01s, but

drawings and the follow- Patented Ma 9,1922.

Serial No. 333,237. 5

section. Fig. 3 is a central vertical section through a pot or receptacle with a cam shaft therein whilebeing heated in'a furnace.

The process consists. of combining with any suitable carburizing material, in powdered or granular form, material for causing the particles thereof to adhere together and form a plastic mass 10,:like putty or dough. This plastic mass may be formed in various ways and byvarious means as desired. For instance, a twenty per cent mixture of heavy tar or equivalent material with the carburizing material, in powdered or ranular form, will produce said plastic material, but the invention. isnot limited to the means for forming such plastic material.

After the carburizing material has been converted into putty-like plastic form, a tape of carburizing material is formed by taking a relatively narrow strip of burlap or other coarse cloth 11, and uniting with it the plastic material so that the plastic material will lie on both sides of the strip of burlap and pass through itsinterstices and make a tape like strip of carburizing material, from oneeighth to one-fourth'of an inch thick.

The third step in this process consists in spirally wrapping the metal article, such as the rod 12 with such carburizing material in its tape like form and draw it very tightly as the rod is wrapped so as to cause the carburizing material to come in very close contact with and adhere directly to the surface of the metal. This can be done because of the use of the relatively narrow strip of cloth, as said strip not only holds the carburizing material in tape like form before and as it is being applied to the metal artiit enables the material to be wrapped tightly around the article and also has a tendency to hold the material on the article during the carburization process. Only such portion of the metal articles as is desired to be carburized is wrapped or covered with the carburizing material.

The next step of the process consists in placing the metal article thus wrapped with its individual supply of carburizing material in the pot or receptacle 13, which is sealed by the cap 14:, and fine clay or sealing material, and then placed in the furnace and heated in the usual way for carburizing or case hardening the metal.

In Figs. 2 and 3 the wrapping or covering of a cam shaft 15 is illustrated.

It is wrapped by the same sort of tape construction, with a combination of carburizing material and strip of burlap or other cloth, and then to draw and hold the covering more snugly around the irregularities of such construction as a cam shaft, the same may be bound I on the outside by wire 16. When such wire is used it is desirable that the plastic carburizing material should be relatively thick and stiff.

As seen in Fig. 3, which shows the cam shaft in a pot ready forthe furnace, the pot is not filled with carburizingmaterial in powdered or granular form as heretofore so as to require a Very large percent of unnecessary carburizing material which interfers with and retards the carburization. One metal article as shown is covered with a layer of carburizing'material secured to it and there is nothing else in the pot. The result is that the carburization takes'place quickly, as there isnothing to interfere with the application of the heat to the material and the metal article, and the carburizing material is in unusually close contact with the metal article as it adheres thereto. Furthermore the metal article can be removed without cooling the pot and another article be put inand thereby there is no loss of heat. In carburizing processes employed hereto 1 fore the pot has been taken out of the furnace and cooled for every change. VVith this process that is not necessary.

It is seen that this process is particularly adapted for carburizing metal articles which are very irregular in form, and it is also useful when the carburizingmaterial is such as to make it desirable to bind the same with tape 11 or the like upon an article with irregular-surfaces.

The invention claimed is:

' 1. The process of carburizing metal, which process includes combining carburizing ma terial in suitable form with a substance that renders it adherent and plastic applying said plastic material to a relatively narrow strip of cloth or the like so as to form a relatively thick tape of carburizing material, wrapping and securing saidtapelike form of carburizing material spirally on the portion ofthe article to be carburizechand then heating the article with the carburizing material thus secured thereon.

2. The process of carburizing metal, which process includes combining carburizing material in suitable form with a substance that renders it adherent and plastic, applying said plastic material to a strip of cloth or the like so as to form a relatively thick tape of carburizingmaterial, wrapping and se curing said tape-like form of carburizing material spirally on the portion or portions of the article to be carburized, binding the same on its outer side with a fabricated then heating the article with the carburizing ma terial thus secured thereon. I

In witness whereof, we have hereunto affiXed our signatures. GEORGE COLEMAN NIXON. FREDERICK CHARLES RAAB. 

